Wyniki wyszukiwania - Biblioteka Nauki

1

Occlusal load transfer in full-contour ceramic implant fixed denture

100%

Żmudzki J. , Chladek G. , Krawczyk C.

Archives of Materials Science and Engineering

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2015

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tom Vol. 72, nr 2

61--68

EN

Purpose: Many clinicians use dentures with metallic core due to fears of insufficient strength of ceramic bridges. The aim of work was finite element strength analysis of fullcontour ceramic implant supported denture in lateral region. Design/methodology/approach: Finite element analysis (Solidworks) of occlusal load transfer in all-ceramic implant supported denture for missing second premolar, first molar and second molar teeth was made. Bridgework from zirconia was supported on two implants 4x12 mm (diameter x length) placed in bone with good quality and quantity. Model was loaded with lateral maximal occlusal force of 800 N. Findings: In the bridgework in the connector with premolar tooth Huber-Mises stress reached 375 MPa. Stress in implants was about 1000 MPa and small plastic deformation zones can occur close to the implant edge under pressure of abutment. Stress in abutment screw reached about 800 MPa in the first thread root and up to 400 MPa in the shank. Stress in bone tissues around implant neck and slightly lower of the beginning of the thread exceeded 140 MPa. Research limitations/implications: Linear isotropic behavior of materials and tied contact between components were assumed in the model. Practical implications: Detrimental effect of maximal occlusal force on the osseointegration between implant and bone showed that patients must be warned against loading of the denture over normal mastication. Stress in the abutment screw reached dangerous value and specific design to prevent fatigue failure is required. Originality/value: An impact of torsion and oblique bending are rarely considered in investigations. This result is relevant for the design of bridgeworks and graded materials for ceramic restoration.

2

Effect of age hardening on corrosion resistance and hardness of CoCrMo alloys used in dental engineering

100%

Dobrzański L. , Reimann Ł. , Krawczyk C.

Archives of Materials Science and Engineering

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2012

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tom Vol. 57, nr 1

5-12

EN

Purpose: The goal of the study is to research the effect of various time of ageing on corrosion resistance, hardness and structures of Remanium 2000+ Co-Cr-Mo alloys used in prosthodontia. Design/methodology/approach: To investigation was prepared mould, cast in 1430°C and realized the heat treatment: solutioning in 1250°C by 3 hours and then ageing in 850°C by 4, 8, 16 and 24 hours. Electrochemical corrosion examination were made in water center which simulated artificial saliva environment. The evaluation of breakdown potential was realized by recording of anodic polarization curves with use the potentiodynamic methods. Corrosion resistance test were carried out at room temperature and use of the VoltaLabŽ PGP201 system for electrochemical tests. Hardness test were obtained by use the microhardness FM ARS 9000 FUTURE TECH with load 1 kg. Structure observation was made after surface preparation: grinding, polishing and etching by light microscope LEICA MEF4A with the magnification 500x. Findings: The age hardening for Co-Cr-Mo alloys is one of the possible method which effect in forming the hardness. The highest value of hardness were obtain for specimen which was ageing with the longer time. Research alloy characterized dendritic crystals in structure for all realized heat treated process. At specimen after the longer ageing was observed the most of discontinuous precipitation and stacking faults in compare with specimen ageing by 4 hours. The age hardening doesn’t influenced much on electrochemical results and only the open circuit potential changed by decreased while increased ageing time. The values of breakdown potential and repassivation potential kept at a constant level. Practical implications: Research material is used on dentures so it’s demand that their characterized corrosion resistance and result of this work make up an information on what heat treatment parameters may be pay attention for CoCrMo alloys. Originality/value: The paper present effect of age hardening especially the ageing time, on the most important criteria of CoCrMo alloys use in dental engineering.

3

Influence of introducing silver nanoparticles on tribological characteristics of soft liner

88%

Chladek G. , Żmudzki J. , Malara P. , Dobrzański L. , Krawczyk C.

Archives of Materials Science and Engineering

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2013

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tom Vol. 62, nr 1

5--14

EN

Purpose: of this paper is to assess the influence of introducing silver nanoparticles to the material intended for denture lining on tribological properties of obtained composite and retention properties of elastic friction attachments made of it. Design/methodology/approach: Studies of coefficient of frictions and forces conducted using a handle designed for this which allows exerting symmetrical pressure through elastomer samples on counterspecimen, applying different pressure forces and relative velocities of friction elements. The study of forces and retention of elastic friction attachments was conducted on the basis of our own methodology in an environment of artificial saliva. Findings: Results of laboratory tests show that introducing 40 ppm of nanosilver does not influence coefficient of friction values. Simultaneously, some dependencies of coefficient of frictions on pressure forces values were observed, while no dependencies of coefficient of frictions on relative velocities of friction elements were shown. No practically meaningful influence of introducing nanosilver, pressure force or relative velocities of elements on friction force values was noted. Values of retention forces did not depend on the content of nanosilver. Research limitations/implications: Limitations resulting from the specificity of the conditions of laboratory tests of retention characteristics do not allow to fully translate obtained results to expected results of clinical trials. Practical implications: The studies show that introducing a small amount of nanosilver to soft lining material will allow to obtain elastic attachments with unchanged retention characteristics, but they will be characterized with increased antimicrobial resistance. Originality/value: Study results of tribological properties of a new composite were presented. Own methodology of studying coefficient of friction and friction force of silicone rubber was presented here.

4

Badania jakości kleszczy ekstrakcyjnych używanych w stomatologii

88%

Drabek K. , Lisoń J. , Krawczyk C. , Radwin E. , Czerwik M.

Aktualne Problemy Biomechaniki

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2018

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tom z. 16

5--11

PL

Celem badań była ocena jakości kleszczy ekstrakcyjnych stosowanych w stomatologii zgodnie z normą PN-EN ISO 9173-1:2006. W ramach badań przeprowadzone zostały badania metalograficzne mikroskopowe, pomiary twardości, obserwacje makroskopowe powierzchni, pomiary chropowatości powierzchni oraz odporności korozyjnej analizowanej postaci narzędzia. Analizowane kleszcze ekstrakcyjne kwalifikujemy do narzędzi nie spełniających określonych zaleceń, ponieważ nie uzyskało wyniku pozytywnego w jednym z wymienionych badań. Na podstawie obserwacji makroskopowych stwierdzono zróżnicowaną ilość rys, wgnieceń oraz wykruszeń.

EN

The aim of the research was to assess the quality of extraction forceps used in dentistry in accordance with the PN-EN ISO 9173-1: 2006 standard. As part of the research, microscopic metallographic examinations, hardness measurements, macroscopic observations of the surface, surface roughness measurements and corrosion resistance of the analyzed tool were carried out. We qualify the extracted extraction tines for tools that do not meet specific recommendations because they did not achieve a positive result in one of the mentioned tests. On the basis of macroscopic observations, a different number of cracks, dents and cracks were found.

5

The influence of silver nanoparticles introduced into RTV-silicone matrix on the activity against Streptococcus mutans

88%

Chladek G. , Mertas A. , Krawczyk C. , Stencel R. , Jabłońska-Stencel E.

Archives of Materials Science and Engineering

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2016

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tom Vol. 78, nr 2

59--65

EN

Purpose: The silicone based room temperature vulcanized (RTV) polymers are commonly used materials for medicine, especially for dentures and maxillofacial prostheses. Unfortunately, the colonization of those materials by pathogenic microorganisms is wellknown problem related with their applications. The aim of presented study was to examine antibacterial properties of RTV silicone for dentistry modified with silver nanoparticles. Design/methodology/approach: The silver nanoparticles were introduced into twocomponent system silicone based materials. The presence of silver nanoparticles was investigated with scanning electron microscope (SEM). The antibacterial activity against Streptococcus mutans was determined. The result were statistically analysed with a Statistica 12.5 software and non-parametric Kruskal-Wallis test (α = 0.05). Findings: The silver nanoparticles introduction into RTV - silicone allowed to enhance the antimicrobial resistance against standard strain of Streptococcus mutans. Research limitations/implications: In this research only Streptococcus mutans bacterium strain was used. In future activity of presented materials against other pathogenic bacteria living in oral cavity should be determined. Additionally long term investigation should be prepared. Practical implications: The colonization of dental materials with pathogenic bacteria and fungus is one of the most important and still unresolved problems related to exposition on oral environment. The low microbiological resistance of RTV-silicones and antimicrobial potential of silver were reported in numerous studies. The gram-positive Streptococcus mutans is commonly found in the human oral cavity and it is an important factor to tooth decay. Originality/value: The resistance against Streptococcus mutans of modified material was enhanced. The investigated materials could be a potential factor a potential conducive to reducing the risk of oral cavity infections.

6

Ocena odporności korozyjnej stopu TI-6AL-4V po obróbce strumieniowo-ściernej stosowanym w protetyce stomatologicznej

88%

Zapart M. , Krawczyk C. , Radwin E. , Czerwik M. , Sarraj S.

Aktualne Problemy Biomechaniki

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2018

|

tom z. 16

41--46

PL

Niniejsza praca dotyczy badań odporności korozyjnej stopu Ti-6Al-4V o zmodyfikowanej powierzchni poprzez obróbkę mechaniczną (szlifowanie, polerowanie oraz obróbka strumieniowo-ścierna) do zastosowań w protetyce stomatologicznej. W ramach pracy przeprowadzono pomiar kąta zwilżania oraz badania odporności na korozje wżerową i szczelinową. Uzyskane wyniki jednoznacznie wykazały, że niezależnie od rodzaju modyfikacji powierzchni stop Ti-6Al-4V ma charakter hydrofilowy i jest odporny na korozję wżerową i szczelinową.

EN

This work concerns tests of corrosion resistance of Ti-6Al-4V alloy with modified surface by mechanical treatment (grinding, polishing and abrasive blasting treatment) for applications in dental prosthetics. As part of the work, was measured the contact angle as well as the pitting and crevice corrosion resistance tests. Obtained results clearly showed that regardless of the type of surface modification, the Ti-6Al-4V alloy is hydrophilic and resistant to pitting and crevice corrosion.

7

The influence of storage conditions on the physicochemical properties and dimensional accuracy of the alginate impressions

88%

Żelezińska K. , Nowak M. , Żmudzki J. , Krawczyk C. , Chladek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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tom Vol. 87, nr 2

68--76

EN

Purpose: Alginate impression materials are the most commonly used masses for taking impressions. They are characterized by good relation of properties to the price. However, the main problem associated with use of the impression masses is dimensions stability. Manufacturers of alginate masses recommend storage impression without any source of moisture, but dentists frequently store impressions wrapped in a wet materials. This may be the a reason of changes in dimensions and other properties. Moreover, it is recognized, that casting the model in the soon after making impression guarantee better dimensional accuracy. However, models are made usually after 24h. For some masses producers claim unequivocally, that the impressions can be stored for up to 168 h without changing the dimensions. So in this study was investigates how storage conditions affect chosen properties of alginate mass, including the accuracy of the models. Design/methodology/approach: Samples were prepared according to the manufacturer instruction and divided into 5 groups. Measurements were made 20 min after taking the impression and after 24h/168h of storage with/ without the resource of moisture. The measurements of Shore A hardness, tensile strength, mass changes and dimensional changes were made. Accuracies of the dental stone models were investigated with models manufactured after 20 min and 168 h after impressions, in comparison to the master model. Findings: The study showed that the storage conditions and time of storage had influence on properties of alginate impression mass. The resource of moisture has got an influence on dimensions and mass changes, tensile strength, elongation and shore A hardness. The results show that the use of the resource of moisture may be a cause of unfavourable changes in the gypsum model dimensions. Research limitations/implications: The storing of the alginate impressions with the resource of moisture is commonly practiced by the doctors, but it inconsistent with the manufacturer's recommendation. Practical implications: The method storing of the alginate impressions determined not only the materials properties, but also the clinical properties of final products like dentures. Originality/value: The significant of the method of the storing of alginate impression materials on the chosen properties of the materials and the accuracy of the dental stone models were shown.

8

Experimental investigation of particle size distribution and morphology of alumina-yttria-ceria-zirconia powders obtained via sol–gel route

75%

Nakonieczny D. S. , Antonowicz M. , Paszenda Z. K. , Radko T. , Drewniak S. , Bogacz W. , Krawczyk C.

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2018

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tom Vol. 38, no. 3

535--543

EN

Background: Oxide-doped zirconia is currently commonly used ceramics in dental prosthetics. However, its use raises a lot of controversy. This is related to the stability of the zirconia metastable phases in the human mouth environment and it sensitivity for the so-called low-temperature degradation. A key way to avoid this type of negative phenomena is doping ZrO2 with selected metal oxide sand choosing appropriate methods for the synthesis of ceramic powders. Objective: The aim of this paper is to present investigations of modification and to analyse the influence of chemical composition and volume of parent-solvent for the morphology and thermal properties of ceramic powders prepared in a ZrO2-CeO2-Y2O3-Al2O3 system. Methods: The powders were obtained by using the sol–gel method in an inert gas atmosphere and ambient temperature using zirconium n-propoxide for this purpose. Morphology was examined by using scanning electron microscopy (SEM) and particle size distribution (PSD); thermal properties was evaluated using thermogravimetric analysis (TGA/DTA/DTG), and chemical composition was confirmed by using electron probe microanalysis (EPMA). Results: Depending from the volume of the CeO2 precursor solution of and regardless of the volume of the second oxide precursor, was observed difference in morphology of the obtained powders. Overall trend is related to reduce the size of agglomerates with an increase in the volume of the precursor of CeO2. Conclusions: The influence of various chemical compositions for morphology and thermal properties is negligible. In contrast, a clear correlation is observed between the volume of parent alcohol for both morphology and thermal properties. Use of sol–gel method to further research in view of these results appears to be appropriate.

9

Effect of silica filler on properties of PMMA resin

75%

Chladek G. , Żmudzki J. , Basa K. , Pater A. , Krawczyk C. , Pakieła W.

Archives of Materials Science and Engineering

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2015

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tom Vol. 71, nr 2

63--72

EN

Purpose: Of this paper was to investigate the effect of silica nanofiller addition to PMMA-based denture material. The null hypothesis was that no difference exists between the mean flexural strength, hardness, sorption among materials without and with different content of silica filler. Design/methodology/approach: The nanosilica was introduced into “powder” component of commercially available PMMA resin for dentistry in concentrations 2, 5 and 10%. The SEM observations were made to confirm dispersion quality. To confirm presence of silica filler the X-ray microanalysis have been made. The influence of nanosilica addition on flexural strength, flexural modulus, hardness and sorption were investigated. Samples were stored at distilled water and ethanol solution. Statistical analysis were prepared with the one-way or the two-way analysis of variance ANOVA ( α =0.05), and Newman-Keuls significant difference post hoc test was used to determine the differences between mean values ( α =0.05). Findings: The result show that all investigated properties were changed after silica filler addition. Initially flexural strength decreased, but after accelerated again in ethanol incised. Flexural modulus and hardness increased. Sorption was decreased in both aging liquids. Research limitations/implications: Limitations resulting from the specificity of the conditions of laboratory tests and aging conditions so it does not allow to fully translate obtained results to expected results of clinical trials. Practical implications: The PMMA drawback is still insufficient mechanical properties, so it can be easily damaged during an accidents or when a patients applies high mastication force to the denture which show areas for further mechanical properties improvement. One of the ways of improving the mechanical properties of PMMA based materials may be nanoparticle addition, including commonly used nanosilica fillers. Originality/value: Influence of destructive plasticizing solutions on chosen properties of materials with different concentrations of silica fillers have been investigated.

10

The properties of experimental silicones reinforced with silica fillers for dentistry

75%

Kalamarz I. , Chladek G. , Pokój M. , Łukowiec D. , Krawczyk C. , Stencel R. , Jabłońska-Stencel E.

Archives of Materials Science and Engineering

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2016

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tom Vol. 81, nr 1

22--29

EN

Purpose: Silicone materials crosslinked during the hydrosilylation reaction are common in dental prosthetics and dentistry. These materials are characterized by a relatively very good properties. However, one of the fundamental problems associated with the use of such polymers is a low resistance to microbial colonization. Numerus fillers with antimicrobial potential have been used experimentally for a decade. Anyway point of concern in this type of work is the use of commercially available materials as the matrix. However, the composition of the matrix for this materials is not clearly known. Therefore, the aim of this study was to obtain a two-component silicone material, crosslinking at room temperature, with properties corresponding to the needs of dental prosthetics, in particular as denture soft linings. Such material would be a starting point to obtain more sophisticated compositions, however, of known composition in full. Design/methodology/approach: As the matrix the mixtures of polymers were prepared. As the “catalyst” component a vinyl polydimethylsiloxane with platinum catalyst in xylene was prepared. As the “base” component a mixture of vinyl polydimethylsiloxane with methylhydrosiloxane - dimethylsiloxane copolymer was made. One of the two fillers differing in the functionalizing was added into prepared substrates (10 or 15% by weight) and ultrasonically homogenized. The Shore A hardness, tensile strength, bond strength to denture base material, water sorption and solubility were investigated. Measurements were made after different aging periods in distilled water at 37±1°C. Findings: The study showed an increase in mechanical properties with increasing concentrations of fillers. The type of filler significantly affects the test results. Increasing the aging time effects on increasing the hardness of materials. Water absorption and solubility were within the desired range. Research limitations/implications: Research limitations/implications The results of the presented research may be generally dependent on technology of fillers introduction into polymers matrix. Practical implications: The results show promising properties of the tested materials. It can be used as starting material for further studies on soft or super soft denture lining and other materials characterized by similar requirements. Originality/value: The method of receiving silicone - based composites with properties required for the selected prosthetic materials, especially denture soft linings was presented. Their properties were similar to commercially available products.